13G Filing: Portolan Capital Management and U.S. Auto Parts Network Inc. (PRTS)

Item 1.

(a)

Name of Issuer
U.S. Auto Parts Network, Inc.

(b)

16941 Keegan Ave.
Carson, CA 90746

Item 2.

(a)

Name of Person Filing
This statement is being filed with respect to the shares of common stock (Common Stock) of the Issuer beneficially owned (1) directly by Portolan Capital Management, LLC, a registered investment adviser, in its capacity as investment manager for various clients, and (2) indirectly by George McCabe, the Manager of Portolan Capital Management, LLC.  Portolan Capital Management, LLC and Mr. McCabe are sometimes individually referred to herein as a Reporting Person and collectively as the Reporting Persons.

(b)

Address of Principal Business Office or, if none, Residence
Portolan Capital Management, LLC and George McCabe
2 International Place, FL 26, Boston, MA 02110

(c)

Citizenship
Portolan Capital Management, LLC DE

Mr. McCabe USA

(d)

Title of Class of Securities
Common

(e)

CUSIP Number
90343C100

Item 3.

If this statement is filed pursuant to §§240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

o

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o).

(b)

o

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).

(c)

o

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c).

(d)

o

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8).

(e)

o

An investment adviser in accordance with §240.13d-1(b)(1)(ii)(E);

(f)

o

An employee benefit plan or endowment fund in accordance with §240.13d-1(b)(1)(ii)(F);

(g)

o

A parent holding company or control person in accordance with §240.13d-1(b)(1)(ii)(G);

(h)

o

A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

o

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

o

A non-U.S. institution in accordance with § 240.13d1(b)(1)(ii)(J);

(k)

o

Group, in accordance with §240.13d-1(b)(1)(ii)(J).